Industrial method for breaking the cell wall of yeast slurry

Abstract

The application discloses an industrial cell wall breaking treatment method for yeast mud, and belongs to the technical field of yeast mud treatment. The method aims at the problems of poor treatment effect, high cost and non-compliance with the environmental protection concept, and comprises the following steps: mixing and stirring, temperature increasing and stirring, temperature decreasing and stirring, heat preservation and separation. The method uses the cell wall breaking method, and adds enzymes corresponding to the degradation of various components of the yeast cell wall, so that the yeast cell wall is degraded, the contents can be released, and the treatment method is efficient. In addition, the reaction condition for the cell wall breaking treatment of the yeast mud is not high, and a general production fermentation tank can meet the requirement. The reaction condition is very mild, and there is no much heat energy operation cost. Since the amount of the added enzyme is very small, the increased cost is also very low. In addition, due to the specificity and high efficiency of the enzyme, the amount of the added exogenous substance is also reduced, the reaction condition is lowered, the treatment cost is greatly reduced, and the treatment method complies with the environmental protection production concept.

Description

Technical Field

[0001] The invention belongs to the technical field of yeast sludge treatment, and particularly relates to an industrial yeast sludge treatment method by breaking the yeast cell wall. Background Art

[0002] Yeast is a commonly used strain in the fermentation industry. It has the advantages of high yield, simple and stable process, but it also has the characteristic of large bacterial volume. For fermentation processes that do not require yeast, its bacterial body (bacterial mud) is waste and needs to be treated.

[0003] The thickness of the yeast cell wall is 0.1 to 0.3 μm, and its weight accounts for 18% to 30% of the cell dry weight. It is mainly composed of two types of polysaccharides, D-glucan and D-mannan, and contains a small amount of protein, fat, and minerals. Approximately equal amounts of glucan and mannan account for 85% of the cell wall dry weight. When the cell ages, the weight of the cell wall will double. The outer layer is mannan, accounting for about 40% to 45% of the cell wall dry weight. The middle layer is a layer of protein molecules, accounting for about 10% of the cell wall dry weight, some of which exist in the form of enzymes bound to the cell wall. The inner layer is glucan.

[0004] Due to the special structure of the cell wall, yeast cells are extremely strong. Under normal circumstances, breaking the yeast cell wall requires ultra-high pressure (above 100Mpa) for at least three minutes, or by adding strong acid and organic solvents. These methods have very high requirements for equipment and are very expensive. In addition, the added wall-breaking reagents will cause secondary pollution, making treatment more difficult.

[0005] In the existing technology, most factories use direct landfill or high-temperature incineration to treat yeast sludge, which will pollute the environment. Therefore, we propose an industrial cell wall breaking method for treating yeast sludge. Summary of the Invention

[0006] The object of the present invention is to provide an industrial yeast cell wall breaking method for treating yeast sludge to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for industrial cell wall breaking and treating yeast sludge, comprising the following steps:

[0008] S1. Mixing and stirring: Add yeast sludge into a fermentation tank containing water, control the mass ratio of yeast sludge to water to be 1:1-5, and perform temperature-controlled and speed-adjusted stirring for 1.5-3 hours;

[0009] S2, temperature rising stirring: by adding lime in the fermentation tank, control the pH of the mixed liquor ≥ 6.5, then sequentially adding β-mannanase with enzyme activity of 15-50 U / L, 50-200 U / L of neutral cellulase and 40-100 U / L of phytase to the fermentation tank, stirring treatment for 5h;

[0010] S3, temperature reduction stirring: reduce the temperature in the fermentation tank in step S2, add nuclease to the fermentation tank, and perform incubation stirring treatment for 3h;

[0011] S4, incubation: adding neutral protease with enzyme activity of 10-200 U / L to the fermentation tank in step S3, and incubating for 4h;

[0012] S5, separation: transferring the product in step S4 to a centrifuge, controlling the separation coefficient ≥ 500, and centrifuging the product in the fermentation tank for ≥ 5min to obtain supernatant and precipitate, respectively.

[0013] It is necessary to note in the scheme that the temperature of the mixed liquor in the fermentation tank in step S1 is controlled to be 48-60℃, and the stirring speed is set to 120-160rpm.

[0014] It is further worth noting that the neutral cellulase in step S2 is replaced by glucanase, and the enzyme activity of the glucanase is ≥ 80 U / L.

[0015] It is further necessary to note that the temperature in the fermentation tank in step S3 is reduced to 37℃, and the amount of nuclease added is 1-1.3mg / g.

[0016] As a preferred embodiment, the obtained supernatant in step S5 is added with 20-30% starch for spray drying, the spray tower temperature is controlled to be 85-90℃, and the centrifugal frequency is 300Hz.

[0017] As a preferred embodiment, the obtained precipitate in step S5 is added with 10% starch for extrusion granulation, the extrusion particle size is controlled to be 40-60 mesh, and the drying temperature is 60-80℃.

[0018] Compared with the prior art, the industrial yeast mud breaking method provided by the present application at least has the following beneficial effects:

[0019] (1) By adopting the method of breaking the wall, adding enzymes corresponding to the degradation of various components of yeast cell wall, thereby degrading the yeast cell wall, so that the contents can be released, the disposal method is efficient, in addition, the reaction condition of the yeast slurry is not high, the general production of fermentation tank can meet it, and the reaction condition is very mild, there is no too much heat energy operation cost, because the amount of enzyme added is very small, the cost increase is also very low, and because of the specificity and efficiency of the enzyme, the amount of exogenous material is also reduced, the reaction condition is reduced, the disposal cost is greatly reduced, and the disposal method conforms to the concept of environmental protection production.

[0020] (2) The final product after separation treatment is a similar substance of the fermentation raw material yeast powder, which can be used as a high-quality nitrogen source and carbon source. For a fermentation plant, the raw material is recycled, which reduces waste discharge and reduces subsequent fermentation cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a process flow diagram of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all.

[0023] Embodiment one

[0024] Please refer to Figure 1 The present application provides an industrial method for breaking the wall of yeast slurry, comprising the following steps:

[0025] S1, mixing and stirring: add the yeast slurry into the fermentation tank containing water, control the mass ratio of yeast slurry to water to be 1:1-5, and carry out temperature control and speed regulation stirring treatment for 1.5-3h;

[0026] In step S1, the temperature of the mixed solution in the fermentation tank is controlled to be 48-60℃, and the stirring speed is set to 120-160rpm.

[0027] S2, temperature rising and stirring: by adding lime in the fermentation tank, control the pH of the mixed solution to be greater than or equal to 6.5, then add β-mannanase with enzyme activity of 15-50U / L, neutral cellulase with enzyme activity of 50-200U / L and phytase with enzyme activity of 40-100U / L into the fermentation tank in turn, and carry out stirring treatment for 5h;

[0028] It is worth noting that the pH range of β-mannanase is pH4~7.5, the effective temperature range of β-mannanase is 30℃ to 65℃, and the optimum temperature range of β-mannanase is 50℃ to 55℃.

[0029] The pH range of the neutral cellulase is pH 3.5-7.5, and the suitable pH is 5.5-6.5; the temperature range is 35-75℃, and the suitable temperature is 50-60℃;

[0030] The suitable pH of the phytase from plant source is 5-7.5, and the suitable temperature of the phytase is 45-60℃;

[0031] Therefore, the lime is added in the fermenter, which can not only raise the temperature in the fermenter, but also adjust the pH of the mixture in the fermenter, so that the degradation of the yeast cell wall by the β-mannanase, the neutral cellulase and the phytase can be effectively improved. That is, the β-mannanase, the neutral cellulase and the phytase which can degrade the components of the yeast cell wall are added in the wall breaking method, so that the yeast cell wall is degraded, and the content can be released. Due to the specificity and high efficiency of the β-mannanase, the neutral cellulase and the phytase, the amount of the added exogenous substances is reduced, and the reaction condition is lowered.

[0032] S3, temperature reduction and stirring: the temperature in the fermenter in step S2 is reduced, and the nuclease is added into the fermenter for temperature holding and stirring for 3h;

[0033] In step S3, the temperature in the fermenter is reduced to 37℃, and the amount of the added nuclease is 1-1.3mg / g.

[0034] S4, temperature holding: the neutral protease with the enzyme activity of 10-200U / L is added into the fermenter in step S3 for temperature holding for 4h;

[0035] S5, separation: the product in step S4 is transferred to a centrifuge, the separation coefficient is controlled to be greater than or equal to 500, and the product in the fermenter is centrifuged for greater than or equal to 5min to obtain supernatant and precipitate respectively;

[0036] In step S5, the obtained supernatant is added with 20-30% starch for spray drying, the temperature of the spray tower is controlled to be 85-90℃, and the centrifugal frequency is 300Hz, so that the dry powder product can be obtained, which can be used to replace the yeast extract powder.

[0037] In step S5, the obtained precipitate is added with 10% starch for extrusion granulation, the extrusion particle size is controlled to be 40-60mesh, and the drying temperature is 60-80℃, so that the carbon source for fermentation can be obtained after drying, and the carbon source can also be used as a carrier for drying or dilution.

[0038] It should be noted that the separation mode of the product in the fermenter in step S5 can also use the filter separation mode with diatomite or perlite as a filter aid.

[0039] Example two,

[0040] The neutral cellulase in step S2 is replaced by glucanase, and the enzyme activity of the glucanase is greater than or equal to 80 U / L.

[0041] It should be noted that the optimal pH range of the glucanase is 6.5 to 7.5, and the optimal temperature range of the glucanase is 50-55℃, so the glucanase can be used to replace the neutral cellulase for degrading the yeast cell wall.

[0042] In summary, according to the above process, it can be known that: by adopting the cell wall breaking method, the enzymes corresponding to the degradation of various components of the yeast cell wall are added in a targeted manner, so as to degrade the yeast cell wall and release the contents. In addition, due to the specificity and high efficiency of the enzyme, the amount of added exogenous substances is also reduced, and the reaction conditions are reduced.

[0043] In terms of the processing process, the reaction conditions for breaking the cell wall of the yeast slurry are not high, and a general production fermentation tank can meet the requirements. The reaction conditions are very mild, and there is no much heat energy operation cost. Since the amount of enzyme added is very small, the increased cost is also very low.

[0044] In terms of the final product, the final product of the present application is an analogue of the fermentation raw material yeast powder, which can be used as a high-quality nitrogen source and carbon source. For a fermentation plant, the raw material is recycled, which reduces waste discharge and reduces subsequent fermentation costs.

[0045] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for industrial cell wall breaking and yeast sludge treatment, characterized in that: The following steps are involved: S1. Mixing and stirring: Add yeast sludge into a fermentation tank containing water, control the mass ratio of yeast sludge to water to be 1:1-5, and perform temperature-controlled and speed-adjusted stirring for 1.5-3 hours; S2. Heating and stirring: lime is added to the fermentation tank to control the pH of the mixed solution to ≥ 6.5, and then 15-50 U / L β-mannanase, 50-200 U / L neutral cellulase, and 40-100 U / L phytase are added to the fermentation tank in sequence, and the mixture is stirred for 5 hours; S3, cooling and stirring: lower the temperature in the fermentation tank in step S2, add nuclease to the fermentation tank, and keep the temperature and stir for 3 hours; S4: Insulation: Add neutral protease with an enzyme activity of 10-200 U / L to the fermentation tank in step S3 and insulate for 4 hours; S5, separation: transfer the product in step S4 to a centrifuge, control the separation coefficient ≥ 500, and centrifuge the product in the fermentation tank for ≥ 5 minutes to obtain a supernatant and a precipitate respectively; In step S1, the temperature of the mixed liquid in the fermentation tank is controlled to 48-60°C, and the stirring speed is set to 120-160 rpm; In step S5, the obtained supernatant is added with 20-30% starch and spray-dried, the spray tower temperature is controlled at 85-90° C., and the centrifugal frequency is 300 Hz; 10% starch is added to the precipitate obtained in step S5, and the mixture is extruded and granulated. The extruded particle size is controlled to be 40-60 mesh, and the drying temperature is 60-80°C.

2. A method for industrial cell wall breaking and yeast sludge treatment according to claim 1, characterized in that: In step S3, the temperature in the fermentation tank is lowered to 37° C., and the amount of the nuclease added is 1-1.3 mg / g.

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